KR102193340B1 - Primary circulating pump assembly - Google Patents

Abstract

The present invention relates to non-displacement pumps, and can be used in a main circulation pump unit of a nuclear power plant, and a first coolant circuit of a nuclear power plant.
The main circulation pump set includes a vertical single-stage vane pump with low impeller position, a pump shaft connected to the engine shaft by a rigid coupling, and a radial axial bearing installed in the upper chamber of the electric engine. Radial axial bearings are installed in the upper chamber of the electric engine and consist of two basic elements.
The radial bearing is mounted on the cylindrical part of the collar mounted on the engine shaft by conical fitting and is manufactured in the form of a rotating metal bushing fixed with a bolt and a pressure flange at the upper end of the engine shaft and a stator bush of a friction reducing material. In addition, an axial bearing composed of two stator lever-type balance arm systems in which a cover plate of a friction reducing material and a rotor lining of a friction reducing material are installed on a flat part of the collar is installed.
The cooling of the radial axial bearings is carried out by water in the nuclear power plant system, which is placed on top of the radial axial bearing collar and is pressed from a screw pump with a stator and threaded rotor bushing.
The object of the present invention is to reduce the load applied to the axial bearing, increase the reliability, and shorten the repair and replacement time of the axial bearing.

Description

Main circulation pump unit {PRIMARY CIRCULATING PUMP ASSEMBLY}

The proposed technical solution relates to a non-displacement pump for liquids with rotational motion of the operating elements, and can be mainly used in nuclear power plants with main circulation pump units targeting the cooling water circuit of nuclear power plants passing through the reactor.

The main components of the main circulation pump unit are as follows.

-Life of bearing friction pairs of main circulation unit

-By ensuring the maintainability of the main circulation pump unit during the operation of a nuclear power plant, it allows revision, repair and replacement of individual components and components with the minimum possible labor and time costs. In this case, the maintainability of the main circulation pump unit determines the good holding capacity of the radial-axial bearing of the pump component. It is desirable to reduce the time spent by maintenance personnel near the installation site at the nuclear power plant of the unit being repaired and to reduce the amount of decontamination required during installation and dismantling.

The main circulation pump unit -1391 is known for use in units of nuclear power plants with VVER -1000 and VVER -1200. The main circulation pump set -1391 represents a vertical feed pump unit with a mechanical shaft seal. The pump unit consists of two independent parts: the pump part and the electric engine. The shaft of the pump part is connected to the engine shaft via a flexible plate coupling that transmits engine torque to the shaft of the pump part. The shaft of the pump component rotates with two independent bearings. The engine shaft rotates with two independent radial bearings and a thrust bearing that senses the weight of the electric engine rotor. The lower radial bearing of the pump part is lubricated by the working medium and cooled with water. The radial axial bearing of the pump is located between the lower radial bearing and the rigid coupling. The radial axial bearings of the pump part are cooled by water, and a metal rotor (rotor) bush, a stator bush of antifriction material, and an antifriction cover plates made of siliconized graphite. It is composed of an axial bearing.

The axial bearing consequently senses the axial force. The axial force includes the pressure of the working medium in the hydraulic casing, the hydrodynamic force on the impeller and the buoyant force directed upward by the weight of the rotor (rotor) of the pump part. The elevated buoyancy significantly exceeds the downward hydrodynamic force on the impeller and the weight of the rotor of the shaft of the pump. The axial load on the bearing significantly exceeds the radial load. Therefore, repairs and revisions of the antifriction cover plates of the axial bearing of the main circulation unit are performed at least 2 times more often than the antifriction (gamma) sleeve (bush) of the radial bearing. . For revision and repair of radial axial bearings, remove the coupling, disassemble the engine, disassemble the radial axial bearing housing and disassemble it together with the elements of the radial axial bearing, then repair the region. Must be transported.

Therefore, the disadvantages of this design of the main circulation pump unit are as follows.

-Not sufficiently compensated by other forces acting on the rotor of the pump, buoyancy acting on the axial bearings;

-Is the need to dismantle the electric engine for the revision and replacement of most wear bearing elements, especially those with infectious linings of radial axial bearings. “The main circulation pump of a nuclear power plant”. -Secondary revision supplement. -Moscow.: Energoatomizdat, 1990, pp. 32-34 (Fig. 2.5)]

According to this method, the shaft of the pump and the electric engine are connected by a rigid coupling, which has three radial bearings. There are two radial bearings on the engine and one radial bearing on the pump. The bearings of the pump are lubricated by the working medium. According to this planning design, the main circulation pump unit for the nuclear power plant "Loviisa" was developed. [Mitenkov F.M., Novinsky E.G., Budov V.M. “The main circulation pump of a nuclear power plant”. -Secondary revision supplement. -Moscow.: Energoatomizdat, 1990, pp. 192-194 (Fig. 2.5)]. Oil-lubricated axial bearings are used in this main circulation pump unit.

The disadvantage of this design is the presence of an oil system that reduces the fire safety of the nuclear power plant system.

The object of the present invention is to install an axial bearing in the upper chamber of the electric engine, not in the pump part when the main circulation pump unit operates, to reduce the load on the axial bearing, compensate for the axial thrust force, and The weight of the electric engine and rotary is transferred to the axial bearing to supply water to the radial bearing. An additional purpose is to improve the maintainability of the main circulation pump unit.

Using the invention the following technical results can in particular be obtained:

-First, reduce the load on the axial bearing.

-Second, it increases reliability.;

-Third, the repair and replacement time of the axial bearing is shortened.

As a solution to the problem, in order to achieve the effect with the specified properties, the main circulation pump unit mainly contains the following for the power unit with the light water furnace cooling water of the nuclear power plant:

-Vertical blade single stage cantilever pump,

-An electric engine installed in the upper chamber and comprising radial-axial bearings that receive all axial loads acting on the unit's rotor, including loads from the hydraulic pressure of the main circuit of the nuclear power plant,

-Built-in screw pump mounted on top of radial axial bearings,

-Lower radial bearing installed in the lower chamber,

-A flywheel located at the bottom of the rotor of an electric engine,

-The shaft of an electric engine connected to the pump shaft by a rigid coupling.

The radial axial bearing installed in the upper chamber of the electric engine consists of two basic elements: the radial bearing and the axial bearing as follows.

-The radial bearing is mounted on the cylindrical part of the collar mounted on the engine shaft by conical fitting, and is in the form of a rotating metal bushing fixed with bolts and pressure flanges at the upper end of the engine shaft and a stator bush of a friction reducing material. Made with.,

-And the axial bearing is composed of two stator lever-type balance arm systems in which the cover plate of friction reducing material and the rotor lining are installed on the flat part of the collar.

Since the upper chamber of the electric engine (electric motor) is made in the form of a sealed stainless steel tank with easy access to the radial axial bearings, time is reduced when repairing and replacing the radial axial bearings.

Therefore, there is no need to perform the work of disassembling the electric engine (electric motor) of the main circulation pump unit for modification and repair of the radial axial bearing.

The water for lubrication of the bearing entering the upper chamber is pressed by a screw pump consisting of a threaded bushing installed at the top of the collar, pumped through a radial axial bearing, and then through a conversion pipe to the lower part of the electric engine. It is pumped by radial bearings installed in the chamber.

The proposed device is described with reference to the following drawings.
1 is an overall view of a main circulation pump unit.
2 is an upper chamber of an electric engine.
3 is a lower chamber of the electric engine.

The shaft of the pump 2 with the lower radial bearing 3 cooled by the working medium is applied to the shaft 4 of the electric engine by means of a clutch 5 transmitting torque between the shafts and the resulting axial force. It is a vertical blade single stage cantilever pump with a lower position of the impeller 1 to be connected (see Fig. 1).

A radial-axial bearing or axial-radial bearing (6) is installed in the upper chamber of the electric engine to detect all axial loads acting on the unit's rotor. The radial bearing of the electric engine 7 is installed in the lower chamber of the electric engine. The flywheel 8 is mounted under the radial lower radial bearing of the engine.

In the main circulation pump unit, lubricating water is supplied from the remote cooler of the nuclear power plant system to the upper chamber 10 of the electric engine via conduit (pipe line) 9. The conduit 9 is connected to the upper chamber by a flange connector 11. The upper chamber 10 is a sealed structure made of stainless steel made in a cylindrical shape. The upper chamber 10 is made in the form of a housing 12 (FIG. 2) to which the stator elements of radial axial bearings are bolted, and a closed top cylinder with a flange connector at the bottom. The tank is detachably fixed to the body 12 by bolts 14.

The collar 15 of the radially axial bearing is mounted on the engine shaft by a conical fit. Attachment of the collar 15 is carried out by means of a bolt 16 and a pressure flange 17 to the upper end of the shaft. The cover plate 18 is mounted on the flat portion of the bearing collar 15. The metal bushing 19 of the upper radial bearing is mounted on the cylindrical part of the collar 15. At the top of the collar is a threaded metal bushing (20). Together with the screwed bush 21 fixed immobile on the stator portion of the radial axial bearing, it forms a screw pump for circulating cooling liquid during operation of the pump unit. The radial bearing body 22 is bolted to the body 12. An upper stator thrust ring 23 is mounted between the radial bearing body 22 and the collar 15. The upper stator thrust ring 23 is composed of a lever type balancing arm system and a cover plate of a friction reducing material. A lower thrust ring of similar design is installed between the collar 15 and the lower part of the body 12.

A mechanical seal 24 is installed at the bottom of the upper chamber to prevent water from entering the engine's stator cavity. The leak of the seal enters the discharge pipe 25, and the discharge pipe 25 is connected to the leak collector 27 through a flange connection 26 (Fig. 1).

A discharge pipe 28 is welded to the lower portion of the main body 12, and the discharge pipe is connected to the auxiliary pipe 30 by a flange connection 29, which is a pipe firmly fixed to the outer wall of the engine.

The water for bearing lubrication entering the upper chamber receives a pressing force from a screw pump formed by a threaded bushing, is pumped through a radial axial bearing, and then flows through the outlet pipe into the transition pipeline. The conveying line is connected to the suction pipe 32 (FIG. 3) welded into the body of the lower chamber 33 via a flange connection 31. The lower chamber body is of a sealed cylindrical stainless steel construction on which the radial bearings 7 of the engine are mounted. The upper mechanical seal 34 is mounted on top of the body to prevent leakage into the stator cavity. A mechanical seal 35 is mounted on the lower end of the body to prevent leakage into the cavity under the engine. The lower radial bearing of the engine includes a stator bush 37 of a friction reducing material fixed to the bearing body 38 which is sequentially fixed to the lower chamber body 33 by fastening an engine shaft and a bolt, and a steel bush 36 mounted on the engine shaft. )to be. Under the action of the head of the screw pump, the water entering the intake port of the lower chamber lubricates the lower radial bearing and exits by a flange connection 41 from the lower chamber along the welded outlet branch pipe 39 (Fig. 1). It is discharged through the discharge pipe 40 connected to the branch pipe. Water is supplied to the remote cooler of the nuclear power plant by the discharge pipe.

To repair radial axial bearings, unscrew bolts (14) and disassemble tank (13), open and disassemble radial bearing body (22), unscrew bolts (16) and pressure flange (17) for clamping. It is sufficient to disassemble and remove the collar 15 and the stator thrust ring of the radially axial bearing 23.

Therefore, to increase reliability in the present invention, a radial axial bearing using water as a lubricant is installed in the upper chamber (room) of the electric engine, not the pump body, and a rigid clutch is used to transmit the axial force and torque. It is achieved by doing. This makes it possible to use the weight of the engine rotor with the flywheel to offset the repulsive force and weaken the remaining force, resulting in less load on the bearing.

Claims (1)

The main circulation pump unit is a vertical blade single stage pump with a low position of the impeller, a lower radial bearing located on the pump shaft above the impeller and lubricated by the pumped medium, a form of a multistage mechanical seal assembly located above the lower radial bearing. It includes a pump shaft sealing assembly made of and a flywheel mounted under the radial bearing of an electric motor,
The pump unit,
-A pump shaft connected to the engine shaft by a rigid coupling,
-It is installed in the upper chamber of the electric engine and contains a radial axial bearing consisting of two main elements: a radial bearing and an axial bearing;
The radial bearing is mounted on the cylindrical part of the collar mounted on the engine shaft by conical fitting, and manufactured in the form of a rotating metal bushing fixed with a bolt and a pressure flange at the upper end of the engine shaft and a stator bush of a friction reducing material. And, the axial bearing is installed on the flat part of the collar and consists of a two stator lever-type balance arm system with a cover plate of a friction reducing material and a rotor cover plate of a friction reducing material. Become;
The cooling of the radial axial bearing is performed by water of a nuclear power plant system, which is placed on the upper end of the radial axial bearing collar and is subjected to pressure from a screw pump having a threaded rotor bushing and a stator;
Water from the upper chamber of the electric engine is supplied to the lower chamber of the electric engine made in the form of a stainless steel cylinder through a pipe installed on the engine wall, and friction with the radial bearing of the electric engine made in the form of a rotor metal bushing. Lubricate the stator bushing made of attenuating material;
The main circulation pump unit, characterized in that the water from the lower chamber of the electric engine is returned to the nuclear power generation system through a discharge pipe.

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